// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_LOADER_STREAM_WRITER_H_
#define CONTENT_BROWSER_LOADER_STREAM_WRITER_H_

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "content/browser/streams/stream_write_observer.h"

class GURL;

namespace net {
class IOBuffer;
}

namespace content {

class ResourceController;
class Stream;
class StreamRegistry;

// StreamWriter is a helper class for ResourceHandlers which route their output
// into a Stream. It manages an internal buffer and handles back-pressure from
// the Stream's reader.
class StreamWriter : public StreamWriteObserver {
public:
    // Creates a new StreamWriter without an initialized Stream or controller. The
    // controller must be set before the writer is used.
    StreamWriter();
    ~StreamWriter() override;

    Stream* stream() { return stream_.get(); }

    void set_controller(ResourceController* controller)
    {
        controller_ = controller;
    }

    // When immediate mode is enabled, the |stream_| is flushed every time new
    // data is made available by calls to OnReadCompleted.
    void set_immediate_mode(bool enabled) { immediate_mode_ = enabled; }

    // Initializes the writer with a new Stream in |registry|. |origin| will be
    // used to construct the URL for the Stream. See WebCore::BlobURL and and
    // WebCore::SecurityOrigin in Blink to understand how origin check is done on
    // resource loading.
    void InitializeStream(StreamRegistry* registry,
        const GURL& origin);

    // Prepares a buffer to read data from the request. This call will be followed
    // by either OnReadCompleted (on successful read or EOF) or destruction.  The
    // buffer may not be recycled until OnReadCompleted is called. If |min_size|
    // is not -1, it is the minimum size of the returned buffer.
    //
    // OnWillRead may be called before the stream is initialized. This is to
    // support MimeTypeResourceHandler which reads the initial chunk of data
    // early.
    void OnWillRead(scoped_refptr<net::IOBuffer>* buf,
        int* buf_size,
        int min_size);

    // A read was completed, forward the data to the Stream. If |*defer| is set to
    // true, the implementation must not continue to process the request until
    // Resume is called on |controller_|.
    //
    // InitializeStream must have been called before calling OnReadCompleted.
    void OnReadCompleted(int bytes_read, bool* defer);

    // Called when there is no more data to read to the stream.
    void Finalize(int status);

private:
    // StreamWriteObserver implementation.
    void OnSpaceAvailable(Stream* stream) override;
    void OnClose(Stream* stream) override;

    ResourceController* controller_;
    scoped_refptr<Stream> stream_;
    scoped_refptr<net::IOBuffer> read_buffer_;
    bool immediate_mode_;

    DISALLOW_COPY_AND_ASSIGN(StreamWriter);
};

} // namespace content

#endif // CONTENT_BROWSER_LOADER_STREAM_WRITER_H_
